// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/compiler.h"

#include <algorithm>
#include <memory>

#include "src/api-inl.h"
#include "src/asmjs/asm-js.h"
#include "src/assembler-inl.h"
#include "src/ast/prettyprinter.h"
#include "src/ast/scopes.h"
#include "src/base/optional.h"
#include "src/bootstrapper.h"
#include "src/compilation-cache.h"
#include "src/compiler-dispatcher/compiler-dispatcher.h"
#include "src/compiler-dispatcher/optimizing-compile-dispatcher.h"
#include "src/compiler/pipeline.h"
#include "src/debug/debug.h"
#include "src/debug/liveedit.h"
#include "src/frames-inl.h"
#include "src/globals.h"
#include "src/heap/heap-inl.h"
#include "src/interpreter/interpreter.h"
#include "src/isolate-inl.h"
#include "src/log-inl.h"
#include "src/message-template.h"
#include "src/objects/feedback-cell-inl.h"
#include "src/objects/map.h"
#include "src/optimized-compilation-info.h"
#include "src/ostreams.h"
#include "src/parsing/parse-info.h"
#include "src/parsing/parser.h"
#include "src/parsing/parsing.h"
#include "src/parsing/rewriter.h"
#include "src/parsing/scanner-character-streams.h"
#include "src/runtime-profiler.h"
#include "src/snapshot/code-serializer.h"
#include "src/unoptimized-compilation-info.h"
#include "src/vm-state-inl.h"
#include "src/zone/zone-list-inl.h" // crbug.com/v8/8816

namespace v8 {
namespace internal {

    // A wrapper around a OptimizedCompilationInfo that detaches the Handles from
    // the underlying DeferredHandleScope and stores them in info_ on
    // destruction.
    class CompilationHandleScope final {
    public:
        explicit CompilationHandleScope(Isolate* isolate,
            OptimizedCompilationInfo* info)
            : deferred_(isolate)
            , info_(info)
        {
        }
        ~CompilationHandleScope() { info_->set_deferred_handles(deferred_.Detach()); }

    private:
        DeferredHandleScope deferred_;
        OptimizedCompilationInfo* info_;
    };

    // Helper that times a scoped region and records the elapsed time.
    struct ScopedTimer {
        explicit ScopedTimer(base::TimeDelta* location)
            : location_(location)
        {
            DCHECK_NOT_NULL(location_);
            timer_.Start();
        }

        ~ScopedTimer() { *location_ += timer_.Elapsed(); }

        base::ElapsedTimer timer_;
        base::TimeDelta* location_;
    };

    namespace {

        void LogFunctionCompilation(CodeEventListener::LogEventsAndTags tag,
            Handle<SharedFunctionInfo> shared,
            Handle<Script> script,
            Handle<AbstractCode> abstract_code, bool optimizing,
            double time_taken_ms, Isolate* isolate)
        {
            DCHECK(!abstract_code.is_null());
            DCHECK(!abstract_code.is_identical_to(BUILTIN_CODE(isolate, CompileLazy)));

            // Log the code generation. If source information is available include
            // script name and line number. Check explicitly whether logging is
            // enabled as finding the line number is not free.
            if (!isolate->logger()->is_listening_to_code_events() && !isolate->is_profiling() && !FLAG_log_function_events && !isolate->code_event_dispatcher()->IsListeningToCodeEvents()) {
                return;
            }

            int line_num = Script::GetLineNumber(script, shared->StartPosition()) + 1;
            int column_num = Script::GetColumnNumber(script, shared->StartPosition()) + 1;
            String script_name = script->name()->IsString()
                ? String::cast(script->name())
                : ReadOnlyRoots(isolate).empty_string();
            CodeEventListener::LogEventsAndTags log_tag = Logger::ToNativeByScript(tag, *script);
            PROFILE(isolate, CodeCreateEvent(log_tag, *abstract_code, *shared, script_name, line_num, column_num));
            if (!FLAG_log_function_events)
                return;

            DisallowHeapAllocation no_gc;

            std::string name = optimizing ? "optimize" : "compile";
            switch (tag) {
            case CodeEventListener::EVAL_TAG:
                name += "-eval";
                break;
            case CodeEventListener::SCRIPT_TAG:
                break;
            case CodeEventListener::LAZY_COMPILE_TAG:
                name += "-lazy";
                break;
            case CodeEventListener::FUNCTION_TAG:
                break;
            default:
                UNREACHABLE();
            }

            LOG(isolate, FunctionEvent(name.c_str(), script->id(), time_taken_ms, shared->StartPosition(), shared->EndPosition(), shared->DebugName()));
        }

        ScriptOriginOptions OriginOptionsForEval(Object script)
        {
            if (!script->IsScript())
                return ScriptOriginOptions();

            const auto outer_origin_options = Script::cast(script)->origin_options();
            return ScriptOriginOptions(outer_origin_options.IsSharedCrossOrigin(),
                outer_origin_options.IsOpaque());
        }

    } // namespace

    // ----------------------------------------------------------------------------
    // Implementation of UnoptimizedCompilationJob

    CompilationJob::Status UnoptimizedCompilationJob::ExecuteJob()
    {
        DisallowHeapAccess no_heap_access;
        // Delegate to the underlying implementation.
        DCHECK_EQ(state(), State::kReadyToExecute);
        ScopedTimer t(&time_taken_to_execute_);
        return UpdateState(ExecuteJobImpl(), State::kReadyToFinalize);
    }

    CompilationJob::Status UnoptimizedCompilationJob::FinalizeJob(
        Handle<SharedFunctionInfo> shared_info, Isolate* isolate)
    {
        DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
        DisallowCodeDependencyChange no_dependency_change;
        DisallowJavascriptExecution no_js(isolate);

        // Delegate to the underlying implementation.
        DCHECK_EQ(state(), State::kReadyToFinalize);
        ScopedTimer t(&time_taken_to_finalize_);
        return UpdateState(FinalizeJobImpl(shared_info, isolate), State::kSucceeded);
    }

    void UnoptimizedCompilationJob::RecordCompilationStats(Isolate* isolate) const
    {
        int code_size;
        if (compilation_info()->has_bytecode_array()) {
            code_size = compilation_info()->bytecode_array()->SizeIncludingMetadata();
        } else {
            DCHECK(compilation_info()->has_asm_wasm_data());
            code_size = compilation_info()->asm_wasm_data()->Size();
        }

        Counters* counters = isolate->counters();
        // TODO(4280): Rename counters from "baseline" to "unoptimized" eventually.
        counters->total_baseline_code_size()->Increment(code_size);
        counters->total_baseline_compile_count()->Increment(1);

        // TODO(5203): Add timers for each phase of compilation.
        // Also add total time (there's now already timer_ on the base class).
    }

    void UnoptimizedCompilationJob::RecordFunctionCompilation(
        CodeEventListener::LogEventsAndTags tag, Handle<SharedFunctionInfo> shared,
        Isolate* isolate) const
    {
        Handle<AbstractCode> abstract_code;
        if (compilation_info()->has_bytecode_array()) {
            abstract_code = Handle<AbstractCode>::cast(compilation_info()->bytecode_array());
        } else {
            DCHECK(compilation_info()->has_asm_wasm_data());
            abstract_code = Handle<AbstractCode>::cast(BUILTIN_CODE(isolate, InstantiateAsmJs));
        }

        double time_taken_ms = time_taken_to_execute_.InMillisecondsF() + time_taken_to_finalize_.InMillisecondsF();

        LogFunctionCompilation(tag, shared, parse_info()->script(), abstract_code,
            false, time_taken_ms, isolate);
    }

    // ----------------------------------------------------------------------------
    // Implementation of OptimizedCompilationJob

    CompilationJob::Status OptimizedCompilationJob::PrepareJob(Isolate* isolate)
    {
        DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
        DisallowJavascriptExecution no_js(isolate);

        if (FLAG_trace_opt && compilation_info()->IsOptimizing()) {
            StdoutStream os;
            os << "[compiling method " << Brief(*compilation_info()->closure())
               << " using " << compiler_name_;
            if (compilation_info()->is_osr())
                os << " OSR";
            os << "]" << std::endl;
        }

        // Delegate to the underlying implementation.
        DCHECK_EQ(state(), State::kReadyToPrepare);
        ScopedTimer t(&time_taken_to_prepare_);
        return UpdateState(PrepareJobImpl(isolate), State::kReadyToExecute);
    }

    CompilationJob::Status OptimizedCompilationJob::ExecuteJob()
    {
        DisallowHeapAccess no_heap_access;
        // Delegate to the underlying implementation.
        DCHECK_EQ(state(), State::kReadyToExecute);
        ScopedTimer t(&time_taken_to_execute_);
        return UpdateState(ExecuteJobImpl(), State::kReadyToFinalize);
    }

    CompilationJob::Status OptimizedCompilationJob::FinalizeJob(Isolate* isolate)
    {
        DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
        DisallowJavascriptExecution no_js(isolate);

        // Delegate to the underlying implementation.
        DCHECK_EQ(state(), State::kReadyToFinalize);
        ScopedTimer t(&time_taken_to_finalize_);
        return UpdateState(FinalizeJobImpl(isolate), State::kSucceeded);
    }

    CompilationJob::Status OptimizedCompilationJob::RetryOptimization(
        BailoutReason reason)
    {
        DCHECK(compilation_info_->IsOptimizing());
        compilation_info_->RetryOptimization(reason);
        return UpdateState(FAILED, State::kFailed);
    }

    CompilationJob::Status OptimizedCompilationJob::AbortOptimization(
        BailoutReason reason)
    {
        DCHECK(compilation_info_->IsOptimizing());
        compilation_info_->AbortOptimization(reason);
        return UpdateState(FAILED, State::kFailed);
    }

    void OptimizedCompilationJob::RecordCompilationStats(CompilationMode mode,
        Isolate* isolate) const
    {
        DCHECK(compilation_info()->IsOptimizing());
        Handle<JSFunction> function = compilation_info()->closure();
        double ms_creategraph = time_taken_to_prepare_.InMillisecondsF();
        double ms_optimize = time_taken_to_execute_.InMillisecondsF();
        double ms_codegen = time_taken_to_finalize_.InMillisecondsF();
        if (FLAG_trace_opt) {
            PrintF("[optimizing ");
            function->ShortPrint();
            PrintF(" - took %0.3f, %0.3f, %0.3f ms]\n", ms_creategraph, ms_optimize,
                ms_codegen);
        }
        if (FLAG_trace_opt_stats) {
            static double compilation_time = 0.0;
            static int compiled_functions = 0;
            static int code_size = 0;

            compilation_time += (ms_creategraph + ms_optimize + ms_codegen);
            compiled_functions++;
            code_size += function->shared()->SourceSize();
            PrintF("Compiled: %d functions with %d byte source size in %fms.\n",
                compiled_functions, code_size, compilation_time);
        }
        // Don't record samples from machines without high-resolution timers,
        // as that can cause serious reporting issues. See the thread at
        // http://g/chrome-metrics-team/NwwJEyL8odU/discussion for more details.
        if (base::TimeTicks::IsHighResolution()) {
            Counters* const counters = isolate->counters();
            if (compilation_info()->is_osr()) {
                counters->turbofan_osr_prepare()->AddSample(
                    static_cast<int>(time_taken_to_prepare_.InMicroseconds()));
                counters->turbofan_osr_execute()->AddSample(
                    static_cast<int>(time_taken_to_execute_.InMicroseconds()));
                counters->turbofan_osr_finalize()->AddSample(
                    static_cast<int>(time_taken_to_finalize_.InMicroseconds()));
                counters->turbofan_osr_total_time()->AddSample(
                    static_cast<int>(ElapsedTime().InMicroseconds()));
            } else {
                counters->turbofan_optimize_prepare()->AddSample(
                    static_cast<int>(time_taken_to_prepare_.InMicroseconds()));
                counters->turbofan_optimize_execute()->AddSample(
                    static_cast<int>(time_taken_to_execute_.InMicroseconds()));
                counters->turbofan_optimize_finalize()->AddSample(
                    static_cast<int>(time_taken_to_finalize_.InMicroseconds()));
                counters->turbofan_optimize_total_time()->AddSample(
                    static_cast<int>(ElapsedTime().InMicroseconds()));

                // Compute foreground / background time.
                base::TimeDelta time_background;
                base::TimeDelta time_foreground = time_taken_to_prepare_ + time_taken_to_finalize_;
                switch (mode) {
                case OptimizedCompilationJob::kConcurrent:
                    time_background += time_taken_to_execute_;
                    break;
                case OptimizedCompilationJob::kSynchronous:
                    time_foreground += time_taken_to_execute_;
                    break;
                }
                counters->turbofan_optimize_total_background()->AddSample(
                    static_cast<int>(time_background.InMicroseconds()));
                counters->turbofan_optimize_total_foreground()->AddSample(
                    static_cast<int>(time_foreground.InMicroseconds()));
            }
        }
    }

    void OptimizedCompilationJob::RecordFunctionCompilation(
        CodeEventListener::LogEventsAndTags tag, Isolate* isolate) const
    {
        Handle<AbstractCode> abstract_code = Handle<AbstractCode>::cast(compilation_info()->code());

        double time_taken_ms = time_taken_to_prepare_.InMillisecondsF() + time_taken_to_execute_.InMillisecondsF() + time_taken_to_finalize_.InMillisecondsF();

        Handle<Script> script(
            Script::cast(compilation_info()->shared_info()->script()), isolate);
        LogFunctionCompilation(tag, compilation_info()->shared_info(), script,
            abstract_code, true, time_taken_ms, isolate);
    }

    // ----------------------------------------------------------------------------
    // Local helper methods that make up the compilation pipeline.

    namespace {

        bool UseAsmWasm(FunctionLiteral* literal, bool asm_wasm_broken)
        {
            // Check whether asm.js validation is enabled.
            if (!FLAG_validate_asm)
                return false;

            // Modules that have validated successfully, but were subsequently broken by
            // invalid module instantiation attempts are off limit forever.
            if (asm_wasm_broken)
                return false;

            // In stress mode we want to run the validator on everything.
            if (FLAG_stress_validate_asm)
                return true;

            // In general, we respect the "use asm" directive.
            return literal->scope()->IsAsmModule();
        }

        void InstallBytecodeArray(Handle<BytecodeArray> bytecode_array,
            Handle<SharedFunctionInfo> shared_info,
            ParseInfo* parse_info, Isolate* isolate)
        {
            if (!FLAG_interpreted_frames_native_stack) {
                shared_info->set_bytecode_array(*bytecode_array);
                return;
            }

            Handle<Code> code = isolate->factory()->CopyCode(Handle<Code>::cast(
                isolate->factory()->interpreter_entry_trampoline_for_profiling()));

            Handle<InterpreterData> interpreter_data = Handle<InterpreterData>::cast(isolate->factory()->NewStruct(
                INTERPRETER_DATA_TYPE, AllocationType::kOld));

            interpreter_data->set_bytecode_array(*bytecode_array);
            interpreter_data->set_interpreter_trampoline(*code);

            shared_info->set_interpreter_data(*interpreter_data);

            Handle<Script> script = parse_info->script();
            Handle<AbstractCode> abstract_code = Handle<AbstractCode>::cast(code);
            int line_num = Script::GetLineNumber(script, shared_info->StartPosition()) + 1;
            int column_num = Script::GetColumnNumber(script, shared_info->StartPosition()) + 1;
            String script_name = script->name()->IsString()
                ? String::cast(script->name())
                : ReadOnlyRoots(isolate).empty_string();
            CodeEventListener::LogEventsAndTags log_tag = Logger::ToNativeByScript(
                CodeEventListener::INTERPRETED_FUNCTION_TAG, *script);
            PROFILE(isolate, CodeCreateEvent(log_tag, *abstract_code, *shared_info, script_name, line_num, column_num));
        }

        void InstallUnoptimizedCode(UnoptimizedCompilationInfo* compilation_info,
            Handle<SharedFunctionInfo> shared_info,
            ParseInfo* parse_info, Isolate* isolate)
        {
            DCHECK_EQ(shared_info->language_mode(),
                compilation_info->literal()->language_mode());

            // Update the shared function info with the scope info.
            Handle<ScopeInfo> scope_info = compilation_info->scope()->scope_info();
            shared_info->set_scope_info(*scope_info);

            if (compilation_info->has_bytecode_array()) {
                DCHECK(!shared_info->HasBytecodeArray()); // Only compiled once.
                DCHECK(!compilation_info->has_asm_wasm_data());
                DCHECK(!shared_info->HasFeedbackMetadata());

                InstallBytecodeArray(compilation_info->bytecode_array(), shared_info,
                    parse_info, isolate);

                Handle<FeedbackMetadata> feedback_metadata = FeedbackMetadata::New(
                    isolate, compilation_info->feedback_vector_spec());
                shared_info->set_feedback_metadata(*feedback_metadata);
            } else {
                DCHECK(compilation_info->has_asm_wasm_data());
                shared_info->set_asm_wasm_data(*compilation_info->asm_wasm_data());
                shared_info->set_feedback_metadata(
                    ReadOnlyRoots(isolate).empty_feedback_metadata());
            }

            // Install coverage info on the shared function info.
            if (compilation_info->has_coverage_info() && !shared_info->HasCoverageInfo()) {
                DCHECK(isolate->is_block_code_coverage());
                isolate->debug()->InstallCoverageInfo(shared_info,
                    compilation_info->coverage_info());
            }
        }

        void EnsureSharedFunctionInfosArrayOnScript(ParseInfo* parse_info,
            Isolate* isolate)
        {
            DCHECK(parse_info->is_toplevel());
            DCHECK(!parse_info->script().is_null());
            if (parse_info->script()->shared_function_infos()->length() > 0) {
                DCHECK_EQ(parse_info->script()->shared_function_infos()->length(),
                    parse_info->max_function_literal_id() + 1);
                return;
            }
            Handle<WeakFixedArray> infos(isolate->factory()->NewWeakFixedArray(
                parse_info->max_function_literal_id() + 1));
            parse_info->script()->set_shared_function_infos(*infos);
        }

        void SetSharedFunctionFlagsFromLiteral(FunctionLiteral* literal,
            Handle<SharedFunctionInfo> shared_info)
        {
            shared_info->set_has_duplicate_parameters(
                literal->has_duplicate_parameters());
            shared_info->set_is_oneshot_iife(literal->is_oneshot_iife());
            shared_info->UpdateAndFinalizeExpectedNofPropertiesFromEstimate(literal);
            if (literal->dont_optimize_reason() != BailoutReason::kNoReason) {
                shared_info->DisableOptimization(literal->dont_optimize_reason());
            }
            shared_info->set_is_safe_to_skip_arguments_adaptor(
                literal->SafeToSkipArgumentsAdaptor());
        }

        CompilationJob::Status FinalizeUnoptimizedCompilationJob(
            UnoptimizedCompilationJob* job, Handle<SharedFunctionInfo> shared_info,
            Isolate* isolate)
        {
            UnoptimizedCompilationInfo* compilation_info = job->compilation_info();
            ParseInfo* parse_info = job->parse_info();

            SetSharedFunctionFlagsFromLiteral(compilation_info->literal(), shared_info);

            CompilationJob::Status status = job->FinalizeJob(shared_info, isolate);
            if (status == CompilationJob::SUCCEEDED) {
                InstallUnoptimizedCode(compilation_info, shared_info, parse_info, isolate);
                CodeEventListener::LogEventsAndTags log_tag;
                if (parse_info->is_toplevel()) {
                    log_tag = compilation_info->is_eval() ? CodeEventListener::EVAL_TAG
                                                          : CodeEventListener::SCRIPT_TAG;
                } else {
                    log_tag = parse_info->lazy_compile() ? CodeEventListener::LAZY_COMPILE_TAG
                                                         : CodeEventListener::FUNCTION_TAG;
                }
                job->RecordFunctionCompilation(log_tag, shared_info, isolate);
                job->RecordCompilationStats(isolate);
            }
            return status;
        }

        std::unique_ptr<UnoptimizedCompilationJob> ExecuteUnoptimizedCompileJobs(
            ParseInfo* parse_info, FunctionLiteral* literal,
            AccountingAllocator* allocator,
            UnoptimizedCompilationJobList* inner_function_jobs)
        {
            if (UseAsmWasm(literal, parse_info->is_asm_wasm_broken())) {
                std::unique_ptr<UnoptimizedCompilationJob> asm_job(
                    AsmJs::NewCompilationJob(parse_info, literal, allocator));
                if (asm_job->ExecuteJob() == CompilationJob::SUCCEEDED) {
                    return asm_job;
                }
                // asm.js validation failed, fall through to standard unoptimized compile.
                // Note: we rely on the fact that AsmJs jobs have done all validation in the
                // PrepareJob and ExecuteJob phases and can't fail in FinalizeJob with
                // with a validation error or another error that could be solve by falling
                // through to standard unoptimized compile.
            }
            std::vector<FunctionLiteral*> eager_inner_literals;
            std::unique_ptr<UnoptimizedCompilationJob> job(
                interpreter::Interpreter::NewCompilationJob(
                    parse_info, literal, allocator, &eager_inner_literals));

            if (job->ExecuteJob() != CompilationJob::SUCCEEDED) {
                // Compilation failed, return null.
                return std::unique_ptr<UnoptimizedCompilationJob>();
            }

            // Recursively compile eager inner literals.
            for (FunctionLiteral* inner_literal : eager_inner_literals) {
                std::unique_ptr<UnoptimizedCompilationJob> inner_job(
                    ExecuteUnoptimizedCompileJobs(parse_info, inner_literal, allocator,
                        inner_function_jobs));
                // Compilation failed, return null.
                if (!inner_job)
                    return std::unique_ptr<UnoptimizedCompilationJob>();
                inner_function_jobs->emplace_front(std::move(inner_job));
            }

            return job;
        }

        std::unique_ptr<UnoptimizedCompilationJob> GenerateUnoptimizedCode(
            ParseInfo* parse_info, AccountingAllocator* allocator,
            UnoptimizedCompilationJobList* inner_function_jobs)
        {
            DisallowHeapAccess no_heap_access;
            DCHECK(inner_function_jobs->empty());

            if (!Compiler::Analyze(parse_info)) {
                return std::unique_ptr<UnoptimizedCompilationJob>();
            }

            // Prepare and execute compilation of the outer-most function.
            std::unique_ptr<UnoptimizedCompilationJob> outer_function_job(
                ExecuteUnoptimizedCompileJobs(parse_info, parse_info->literal(),
                    allocator, inner_function_jobs));
            if (!outer_function_job)
                return std::unique_ptr<UnoptimizedCompilationJob>();

            // Character stream shouldn't be used again.
            parse_info->ResetCharacterStream();

            return outer_function_job;
        }

        MaybeHandle<SharedFunctionInfo> GenerateUnoptimizedCodeForToplevel(
            Isolate* isolate, ParseInfo* parse_info, AccountingAllocator* allocator,
            IsCompiledScope* is_compiled_scope)
        {
            EnsureSharedFunctionInfosArrayOnScript(parse_info, isolate);
            parse_info->ast_value_factory()->Internalize(isolate);

            if (!Compiler::Analyze(parse_info))
                return MaybeHandle<SharedFunctionInfo>();
            DeclarationScope::AllocateScopeInfos(parse_info, isolate);

            // Prepare and execute compilation of the outer-most function.
            // Create the SharedFunctionInfo and add it to the script's list.
            Handle<Script> script = parse_info->script();
            Handle<SharedFunctionInfo> top_level = isolate->factory()->NewSharedFunctionInfoForLiteral(parse_info->literal(),
                script, true);

            std::vector<FunctionLiteral*> functions_to_compile;
            functions_to_compile.push_back(parse_info->literal());

            while (!functions_to_compile.empty()) {
                FunctionLiteral* literal = functions_to_compile.back();
                functions_to_compile.pop_back();
                Handle<SharedFunctionInfo> shared_info = Compiler::GetSharedFunctionInfo(literal, script, isolate);
                if (shared_info->is_compiled())
                    continue;
                if (UseAsmWasm(literal, parse_info->is_asm_wasm_broken())) {
                    std::unique_ptr<UnoptimizedCompilationJob> asm_job(
                        AsmJs::NewCompilationJob(parse_info, literal, allocator));
                    if (asm_job->ExecuteJob() == CompilationJob::SUCCEEDED && FinalizeUnoptimizedCompilationJob(asm_job.get(), shared_info, isolate) == CompilationJob::SUCCEEDED) {
                        continue;
                    }
                    // asm.js validation failed, fall through to standard unoptimized compile.
                    // Note: we rely on the fact that AsmJs jobs have done all validation in
                    // the PrepareJob and ExecuteJob phases and can't fail in FinalizeJob with
                    // with a validation error or another error that could be solve by falling
                    // through to standard unoptimized compile.
                }

                std::unique_ptr<UnoptimizedCompilationJob> job(
                    interpreter::Interpreter::NewCompilationJob(
                        parse_info, literal, allocator, &functions_to_compile));

                if (job->ExecuteJob() == CompilationJob::FAILED || FinalizeUnoptimizedCompilationJob(job.get(), shared_info, isolate) == CompilationJob::FAILED) {
                    return MaybeHandle<SharedFunctionInfo>();
                }

                if (shared_info.is_identical_to(top_level)) {
                    // Ensure that the top level function is retained.
                    *is_compiled_scope = shared_info->is_compiled_scope();
                    DCHECK(is_compiled_scope->is_compiled());
                }
            }

            // Character stream shouldn't be used again.
            parse_info->ResetCharacterStream();

            return top_level;
        }

        bool FinalizeUnoptimizedCode(
            ParseInfo* parse_info, Isolate* isolate,
            Handle<SharedFunctionInfo> shared_info,
            UnoptimizedCompilationJob* outer_function_job,
            UnoptimizedCompilationJobList* inner_function_jobs)
        {
            DCHECK(AllowCompilation::IsAllowed(isolate));

            // TODO(rmcilroy): Clear native context in debug once AsmJS generates doesn't
            // rely on accessing native context during finalization.

            // Allocate scope infos for the literal.
            DeclarationScope::AllocateScopeInfos(parse_info, isolate);

            // Finalize the outer-most function's compilation job.
            if (FinalizeUnoptimizedCompilationJob(outer_function_job, shared_info,
                    isolate)
                != CompilationJob::SUCCEEDED) {
                return false;
            }

            // Finalize the inner functions' compilation jobs.
            for (auto&& inner_job : *inner_function_jobs) {
                Handle<SharedFunctionInfo> inner_shared_info = Compiler::GetSharedFunctionInfo(
                    inner_job->compilation_info()->literal(), parse_info->script(),
                    isolate);
                // The inner function might be compiled already if compiling for debug.
                if (inner_shared_info->is_compiled())
                    continue;
                if (FinalizeUnoptimizedCompilationJob(inner_job.get(), inner_shared_info,
                        isolate)
                    != CompilationJob::SUCCEEDED) {
                    return false;
                }
            }

            // Report any warnings generated during compilation.
            if (parse_info->pending_error_handler()->has_pending_warnings()) {
                parse_info->pending_error_handler()->ReportWarnings(isolate,
                    parse_info->script());
            }

            return true;
        }

        V8_WARN_UNUSED_RESULT MaybeHandle<Code> GetCodeFromOptimizedCodeCache(
            Handle<JSFunction> function, BailoutId osr_offset)
        {
            RuntimeCallTimerScope runtimeTimer(
                function->GetIsolate(),
                RuntimeCallCounterId::kCompileGetFromOptimizedCodeMap);
            Handle<SharedFunctionInfo> shared(function->shared(), function->GetIsolate());
            DisallowHeapAllocation no_gc;
            if (osr_offset.IsNone()) {
                if (function->has_feedback_vector()) {
                    FeedbackVector feedback_vector = function->feedback_vector();
                    feedback_vector->EvictOptimizedCodeMarkedForDeoptimization(
                        function->shared(), "GetCodeFromOptimizedCodeCache");
                    Code code = feedback_vector->optimized_code();

                    if (!code.is_null()) {
                        // Caching of optimized code enabled and optimized code found.
                        DCHECK(!code->marked_for_deoptimization());
                        DCHECK(function->shared()->is_compiled());
                        return Handle<Code>(code, feedback_vector->GetIsolate());
                    }
                }
            }
            return MaybeHandle<Code>();
        }

        void ClearOptimizedCodeCache(OptimizedCompilationInfo* compilation_info)
        {
            Handle<JSFunction> function = compilation_info->closure();
            if (compilation_info->osr_offset().IsNone()) {
                Handle<FeedbackVector> vector = handle(function->feedback_vector(), function->GetIsolate());
                vector->ClearOptimizationMarker();
            }
        }

        void InsertCodeIntoOptimizedCodeCache(
            OptimizedCompilationInfo* compilation_info)
        {
            Handle<Code> code = compilation_info->code();
            if (code->kind() != Code::OPTIMIZED_FUNCTION)
                return; // Nothing to do.

            // Function context specialization folds-in the function context,
            // so no sharing can occur.
            if (compilation_info->is_function_context_specializing()) {
                // Native context specialized code is not shared, so make sure the optimized
                // code cache is clear.
                ClearOptimizedCodeCache(compilation_info);
                return;
            }

            // Cache optimized context-specific code.
            Handle<JSFunction> function = compilation_info->closure();
            Handle<SharedFunctionInfo> shared(function->shared(), function->GetIsolate());
            Handle<Context> native_context(function->context()->native_context(),
                function->GetIsolate());
            if (compilation_info->osr_offset().IsNone()) {
                Handle<FeedbackVector> vector = handle(function->feedback_vector(), function->GetIsolate());
                FeedbackVector::SetOptimizedCode(vector, code);
            }
        }

        bool GetOptimizedCodeNow(OptimizedCompilationJob* job, Isolate* isolate)
        {
            TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
            RuntimeCallTimerScope runtimeTimer(
                isolate, RuntimeCallCounterId::kRecompileSynchronous);
            OptimizedCompilationInfo* compilation_info = job->compilation_info();
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.RecompileSynchronous");

            if (job->PrepareJob(isolate) != CompilationJob::SUCCEEDED || job->ExecuteJob() != CompilationJob::SUCCEEDED || job->FinalizeJob(isolate) != CompilationJob::SUCCEEDED) {
                if (FLAG_trace_opt) {
                    PrintF("[aborted optimizing ");
                    compilation_info->closure()->ShortPrint();
                    PrintF(" because: %s]\n",
                        GetBailoutReason(compilation_info->bailout_reason()));
                }
                return false;
            }

            // Success!
            job->RecordCompilationStats(OptimizedCompilationJob::kSynchronous, isolate);
            DCHECK(!isolate->has_pending_exception());
            InsertCodeIntoOptimizedCodeCache(compilation_info);
            job->RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG, isolate);
            return true;
        }

        bool GetOptimizedCodeLater(OptimizedCompilationJob* job, Isolate* isolate)
        {
            OptimizedCompilationInfo* compilation_info = job->compilation_info();
            if (!isolate->optimizing_compile_dispatcher()->IsQueueAvailable()) {
                if (FLAG_trace_concurrent_recompilation) {
                    PrintF("  ** Compilation queue full, will retry optimizing ");
                    compilation_info->closure()->ShortPrint();
                    PrintF(" later.\n");
                }
                return false;
            }

            if (isolate->heap()->HighMemoryPressure()) {
                if (FLAG_trace_concurrent_recompilation) {
                    PrintF("  ** High memory pressure, will retry optimizing ");
                    compilation_info->closure()->ShortPrint();
                    PrintF(" later.\n");
                }
                return false;
            }

            TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
            RuntimeCallTimerScope runtimeTimer(
                isolate, RuntimeCallCounterId::kRecompileSynchronous);
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.RecompileSynchronous");

            if (job->PrepareJob(isolate) != CompilationJob::SUCCEEDED)
                return false;
            isolate->optimizing_compile_dispatcher()->QueueForOptimization(job);

            if (FLAG_trace_concurrent_recompilation) {
                PrintF("  ** Queued ");
                compilation_info->closure()->ShortPrint();
                PrintF(" for concurrent optimization.\n");
            }
            return true;
        }

        MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
            ConcurrencyMode mode,
            BailoutId osr_offset = BailoutId::None(),
            JavaScriptFrame* osr_frame = nullptr)
        {
            Isolate* isolate = function->GetIsolate();
            Handle<SharedFunctionInfo> shared(function->shared(), isolate);

            // Make sure we clear the optimization marker on the function so that we
            // don't try to re-optimize.
            if (function->HasOptimizationMarker()) {
                function->ClearOptimizationMarker();
            }

            if (shared->optimization_disabled() && shared->disable_optimization_reason() == BailoutReason::kNeverOptimize) {
                return MaybeHandle<Code>();
            }

            if (isolate->debug()->needs_check_on_function_call()) {
                // Do not optimize when debugger needs to hook into every call.
                return MaybeHandle<Code>();
            }

            // If code was pending optimization for testing, delete remove the strong root
            // that was preventing the bytecode from being flushed between marking and
            // optimization.
            if (!isolate->heap()->pending_optimize_for_test_bytecode()->IsUndefined()) {
                Handle<ObjectHashTable> table = handle(ObjectHashTable::cast(
                                                           isolate->heap()->pending_optimize_for_test_bytecode()),
                    isolate);
                bool was_present;
                table = table->Remove(isolate, table, handle(function->shared(), isolate),
                    &was_present);
                isolate->heap()->SetPendingOptimizeForTestBytecode(*table);
            }

            Handle<Code> cached_code;
            if (GetCodeFromOptimizedCodeCache(function, osr_offset)
                    .ToHandle(&cached_code)) {
                if (FLAG_trace_opt) {
                    PrintF("[found optimized code for ");
                    function->ShortPrint();
                    if (!osr_offset.IsNone()) {
                        PrintF(" at OSR AST id %d", osr_offset.ToInt());
                    }
                    PrintF("]\n");
                }
                return cached_code;
            }

            // Reset profiler ticks, function is no longer considered hot.
            DCHECK(shared->is_compiled());
            function->feedback_vector()->set_profiler_ticks(0);

            VMState<COMPILER> state(isolate);
            TimerEventScope<TimerEventOptimizeCode> optimize_code_timer(isolate);
            RuntimeCallTimerScope runtimeTimer(isolate,
                RuntimeCallCounterId::kOptimizeCode);
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.OptimizeCode");

            DCHECK(!isolate->has_pending_exception());
            PostponeInterruptsScope postpone(isolate);
            bool has_script = shared->script()->IsScript();
            // BUG(5946): This DCHECK is necessary to make certain that we won't
            // tolerate the lack of a script without bytecode.
            DCHECK_IMPLIES(!has_script, shared->HasBytecodeArray());
            std::unique_ptr<OptimizedCompilationJob> job(
                compiler::Pipeline::NewCompilationJob(isolate, function, has_script));
            OptimizedCompilationInfo* compilation_info = job->compilation_info();

            compilation_info->SetOptimizingForOsr(osr_offset, osr_frame);

            // Do not use TurboFan if we need to be able to set break points.
            if (compilation_info->shared_info()->HasBreakInfo()) {
                compilation_info->AbortOptimization(BailoutReason::kFunctionBeingDebugged);
                return MaybeHandle<Code>();
            }

            // Do not use TurboFan if optimization is disabled or function doesn't pass
            // turbo_filter.
            if (!FLAG_opt || !shared->PassesFilter(FLAG_turbo_filter)) {
                compilation_info->AbortOptimization(BailoutReason::kOptimizationDisabled);
                return MaybeHandle<Code>();
            }

            // In case of concurrent recompilation, all handles below this point will be
            // allocated in a deferred handle scope that is detached and handed off to
            // the background thread when we return.
            base::Optional<CompilationHandleScope> compilation;
            if (mode == ConcurrencyMode::kConcurrent) {
                compilation.emplace(isolate, compilation_info);
            }

            // All handles below will be canonicalized.
            CanonicalHandleScope canonical(isolate);

            // Reopen handles in the new CompilationHandleScope.
            compilation_info->ReopenHandlesInNewHandleScope(isolate);

            if (mode == ConcurrencyMode::kConcurrent) {
                if (GetOptimizedCodeLater(job.get(), isolate)) {
                    job.release(); // The background recompile job owns this now.

                    // Set the optimization marker and return a code object which checks it.
                    function->SetOptimizationMarker(OptimizationMarker::kInOptimizationQueue);
                    DCHECK(function->IsInterpreted() || (!function->is_compiled() && function->shared()->IsInterpreted()));
                    DCHECK(function->shared()->HasBytecodeArray());
                    return BUILTIN_CODE(isolate, InterpreterEntryTrampoline);
                }
            } else {
                if (GetOptimizedCodeNow(job.get(), isolate))
                    return compilation_info->code();
            }

            if (isolate->has_pending_exception())
                isolate->clear_pending_exception();
            return MaybeHandle<Code>();
        }

        bool FailWithPendingException(Isolate* isolate, ParseInfo* parse_info,
            Compiler::ClearExceptionFlag flag)
        {
            if (flag == Compiler::CLEAR_EXCEPTION) {
                isolate->clear_pending_exception();
            } else if (!isolate->has_pending_exception()) {
                if (parse_info->pending_error_handler()->has_pending_error()) {
                    parse_info->pending_error_handler()->ReportErrors(
                        isolate, parse_info->script(), parse_info->ast_value_factory());
                } else {
                    isolate->StackOverflow();
                }
            }
            return false;
        }

        void FinalizeScriptCompilation(Isolate* isolate, ParseInfo* parse_info)
        {
            Handle<Script> script = parse_info->script();
            script->set_compilation_state(Script::COMPILATION_STATE_COMPILED);

            // Register any pending parallel tasks with the associated SFI.
            if (parse_info->parallel_tasks()) {
                CompilerDispatcher* dispatcher = parse_info->parallel_tasks()->dispatcher();
                for (auto& it : *parse_info->parallel_tasks()) {
                    FunctionLiteral* literal = it.first;
                    CompilerDispatcher::JobId job_id = it.second;
                    MaybeHandle<SharedFunctionInfo> maybe_shared_for_task = script->FindSharedFunctionInfo(isolate, literal);
                    Handle<SharedFunctionInfo> shared_for_task;
                    if (maybe_shared_for_task.ToHandle(&shared_for_task)) {
                        dispatcher->RegisterSharedFunctionInfo(job_id, *shared_for_task);
                    } else {
                        dispatcher->AbortJob(job_id);
                    }
                }
            }
        }

        MaybeHandle<SharedFunctionInfo> FinalizeTopLevel(
            ParseInfo* parse_info, Isolate* isolate,
            UnoptimizedCompilationJob* outer_function_job,
            UnoptimizedCompilationJobList* inner_function_jobs)
        {
            // Internalize ast values onto the heap.
            parse_info->ast_value_factory()->Internalize(isolate);

            // Create shared function infos for top level and shared function infos array
            // for inner functions.
            EnsureSharedFunctionInfosArrayOnScript(parse_info, isolate);
            DCHECK_EQ(kNoSourcePosition,
                parse_info->literal()->function_token_position());
            Handle<SharedFunctionInfo> shared_info = isolate->factory()->NewSharedFunctionInfoForLiteral(
                parse_info->literal(), parse_info->script(), true);

            // Finalize compilation of the unoptimized bytecode or asm-js data.
            if (!FinalizeUnoptimizedCode(parse_info, isolate, shared_info,
                    outer_function_job, inner_function_jobs)) {
                FailWithPendingException(isolate, parse_info,
                    Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
                return MaybeHandle<SharedFunctionInfo>();
            }

            FinalizeScriptCompilation(isolate, parse_info);

            return shared_info;
        }

        MaybeHandle<SharedFunctionInfo> CompileToplevel(
            ParseInfo* parse_info, Isolate* isolate,
            IsCompiledScope* is_compiled_scope)
        {
            TimerEventScope<TimerEventCompileCode> top_level_timer(isolate);
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileCode");
            DCHECK_EQ(ThreadId::Current(), isolate->thread_id());

            PostponeInterruptsScope postpone(isolate);
            DCHECK(!isolate->native_context().is_null());
            RuntimeCallTimerScope runtimeTimer(
                isolate, parse_info->is_eval() ? RuntimeCallCounterId::kCompileEval : RuntimeCallCounterId::kCompileScript);
            VMState<BYTECODE_COMPILER> state(isolate);
            if (parse_info->literal() == nullptr && !parsing::ParseProgram(parse_info, isolate)) {
                return MaybeHandle<SharedFunctionInfo>();
            }
            // Measure how long it takes to do the compilation; only take the
            // rest of the function into account to avoid overlap with the
            // parsing statistics.
            HistogramTimer* rate = parse_info->is_eval()
                ? isolate->counters()->compile_eval()
                : isolate->counters()->compile();
            HistogramTimerScope timer(rate);
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                parse_info->is_eval() ? "V8.CompileEval" : "V8.Compile");

            // Generate the unoptimized bytecode or asm-js data.
            MaybeHandle<SharedFunctionInfo> shared_info = GenerateUnoptimizedCodeForToplevel(
                isolate, parse_info, isolate->allocator(), is_compiled_scope);
            if (shared_info.is_null()) {
                FailWithPendingException(isolate, parse_info,
                    Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
                return MaybeHandle<SharedFunctionInfo>();
            }

            FinalizeScriptCompilation(isolate, parse_info);
            return shared_info;
        }

        std::unique_ptr<UnoptimizedCompilationJob> CompileOnBackgroundThread(
            ParseInfo* parse_info, AccountingAllocator* allocator,
            UnoptimizedCompilationJobList* inner_function_jobs)
        {
            DisallowHeapAccess no_heap_access;
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.CompileCodeBackground");
            RuntimeCallTimerScope runtimeTimer(
                parse_info->runtime_call_stats(),
                parse_info->is_toplevel()
                    ? parse_info->is_eval()
                        ? RuntimeCallCounterId::kCompileBackgroundEval
                        : RuntimeCallCounterId::kCompileBackgroundScript
                    : RuntimeCallCounterId::kCompileBackgroundFunction);

            // Generate the unoptimized bytecode or asm-js data.
            std::unique_ptr<UnoptimizedCompilationJob> outer_function_job(
                GenerateUnoptimizedCode(parse_info, allocator, inner_function_jobs));
            return outer_function_job;
        }

    } // namespace

    BackgroundCompileTask::BackgroundCompileTask(ScriptStreamingData* streamed_data,
        Isolate* isolate)
        : info_(new ParseInfo(isolate))
        , stack_size_(i::FLAG_stack_size)
        , worker_thread_runtime_call_stats_(
              isolate->counters()->worker_thread_runtime_call_stats())
        , allocator_(isolate->allocator())
        , timer_(isolate->counters()->compile_script_on_background())
    {
        VMState<PARSER> state(isolate);

        // Prepare the data for the internalization phase and compilation phase, which
        // will happen in the main thread after parsing.
        LOG(isolate, ScriptEvent(Logger::ScriptEventType::kStreamingCompile, info_->script_id()));
        info_->set_toplevel();
        info_->set_allow_lazy_parsing();
        if (V8_UNLIKELY(info_->block_coverage_enabled())) {
            info_->AllocateSourceRangeMap();
        }
        LanguageMode language_mode = construct_language_mode(FLAG_use_strict);
        info_->set_language_mode(
            stricter_language_mode(info_->language_mode(), language_mode));

        std::unique_ptr<Utf16CharacterStream> stream(ScannerStream::For(
            streamed_data->source_stream.get(), streamed_data->encoding));
        info_->set_character_stream(std::move(stream));
    }

    BackgroundCompileTask::BackgroundCompileTask(
        AccountingAllocator* allocator, const ParseInfo* outer_parse_info,
        const AstRawString* function_name, const FunctionLiteral* function_literal,
        WorkerThreadRuntimeCallStats* worker_thread_runtime_stats,
        TimedHistogram* timer, int max_stack_size)
        : info_(ParseInfo::FromParent(outer_parse_info, allocator, function_literal,
            function_name))
        , stack_size_(max_stack_size)
        , worker_thread_runtime_call_stats_(worker_thread_runtime_stats)
        , allocator_(allocator)
        , timer_(timer)
    {
        DCHECK(outer_parse_info->is_toplevel());
        DCHECK(!function_literal->is_toplevel());

        // Clone the character stream so both can be accessed independently.
        std::unique_ptr<Utf16CharacterStream> character_stream = outer_parse_info->character_stream()->Clone();
        character_stream->Seek(function_literal->start_position());
        info_->set_character_stream(std::move(character_stream));

        // Get preparsed scope data from the function literal.
        if (function_literal->produced_preparse_data()) {
            ZonePreparseData* serialized_data = function_literal->produced_preparse_data()->Serialize(info_->zone());
            info_->set_consumed_preparse_data(
                ConsumedPreparseData::For(info_->zone(), serialized_data));
        }
    }

    BackgroundCompileTask::~BackgroundCompileTask() = default;

    namespace {

        // A scope object that ensures a parse info's runtime call stats, stack limit
        // and on_background_thread fields is set correctly during worker-thread
        // compile, and restores it after going out of scope.
        class OffThreadParseInfoScope {
        public:
            OffThreadParseInfoScope(
                ParseInfo* parse_info,
                WorkerThreadRuntimeCallStats* worker_thread_runtime_stats, int stack_size)
                : parse_info_(parse_info)
                , original_runtime_call_stats_(parse_info_->runtime_call_stats())
                , original_stack_limit_(parse_info_->stack_limit())
                , worker_thread_scope_(worker_thread_runtime_stats)
            {
                parse_info_->set_on_background_thread(true);
                parse_info_->set_runtime_call_stats(worker_thread_scope_.Get());
                parse_info_->set_stack_limit(GetCurrentStackPosition() - stack_size * KB);
            }

            ~OffThreadParseInfoScope()
            {
                parse_info_->set_stack_limit(original_stack_limit_);
                parse_info_->set_runtime_call_stats(original_runtime_call_stats_);
                parse_info_->set_on_background_thread(false);
            }

        private:
            ParseInfo* parse_info_;
            RuntimeCallStats* original_runtime_call_stats_;
            uintptr_t original_stack_limit_;
            WorkerThreadRuntimeCallStatsScope worker_thread_scope_;

            DISALLOW_COPY_AND_ASSIGN(OffThreadParseInfoScope);
        };

    } // namespace

    void BackgroundCompileTask::Run()
    {
        DisallowHeapAllocation no_allocation;
        DisallowHandleAllocation no_handles;
        DisallowHeapAccess no_heap_access;

        TimedHistogramScope timer(timer_);
        OffThreadParseInfoScope off_thread_scope(
            info_.get(), worker_thread_runtime_call_stats_, stack_size_);
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
            "BackgroundCompileTask::Run");
        RuntimeCallTimerScope runtimeTimer(
            info_->runtime_call_stats(),
            RuntimeCallCounterId::kCompileBackgroundCompileTask);

        // Update the character stream's runtime call stats.
        info_->character_stream()->set_runtime_call_stats(
            info_->runtime_call_stats());

        // Parser needs to stay alive for finalizing the parsing on the main
        // thread.
        parser_.reset(new Parser(info_.get()));
        parser_->InitializeEmptyScopeChain(info_.get());

        parser_->ParseOnBackground(info_.get());
        if (info_->literal() != nullptr) {
            // Parsing has succeeded, compile.
            outer_function_job_ = CompileOnBackgroundThread(info_.get(), allocator_,
                &inner_function_jobs_);
        }
    }

    // ----------------------------------------------------------------------------
    // Implementation of Compiler

    bool Compiler::Analyze(ParseInfo* parse_info)
    {
        DCHECK_NOT_NULL(parse_info->literal());
        RuntimeCallTimerScope runtimeTimer(
            parse_info->runtime_call_stats(),
            parse_info->on_background_thread()
                ? RuntimeCallCounterId::kCompileBackgroundAnalyse
                : RuntimeCallCounterId::kCompileAnalyse);
        if (!Rewriter::Rewrite(parse_info))
            return false;
        if (!DeclarationScope::Analyze(parse_info))
            return false;
        return true;
    }

    bool Compiler::ParseAndAnalyze(ParseInfo* parse_info,
        Handle<SharedFunctionInfo> shared_info,
        Isolate* isolate)
    {
        if (!parsing::ParseAny(parse_info, shared_info, isolate)) {
            return false;
        }
        return Compiler::Analyze(parse_info);
    }

    // static
    bool Compiler::CollectSourcePositions(Isolate* isolate,
        Handle<SharedFunctionInfo> shared_info)
    {
        DCHECK(shared_info->is_compiled());
        DCHECK(shared_info->HasBytecodeArray());
        DCHECK(!shared_info->GetBytecodeArray()->HasSourcePositionTable());

        // Collecting source positions requires allocating a new source position
        // table.
        DCHECK(AllowHeapAllocation::IsAllowed());

        Handle<BytecodeArray> bytecode = handle(shared_info->GetBytecodeArray(), isolate);

        // TODO(v8:8510): Push the CLEAR_EXCEPTION flag or something like it down into
        // the parser so it aborts without setting a pending exception, which then
        // gets thrown. This would avoid the situation where potentially we'd reparse
        // several times (running out of stack each time) before hitting this limit.
        if (GetCurrentStackPosition() < isolate->stack_guard()->real_climit()) {
            // Stack is already exhausted.
            bytecode->SetSourcePositionsFailedToCollect();
            return false;
        }

        DCHECK(AllowCompilation::IsAllowed(isolate));
        DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
        DCHECK(!isolate->has_pending_exception());
        VMState<BYTECODE_COMPILER> state(isolate);
        PostponeInterruptsScope postpone(isolate);
        RuntimeCallTimerScope runtimeTimer(
            isolate, RuntimeCallCounterId::kCompileCollectSourcePositions);
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
            "V8.CollectSourcePositions");
        HistogramTimerScope timer(isolate->counters()->collect_source_positions());

        // Set up parse info.
        ParseInfo parse_info(isolate, shared_info);
        parse_info.set_lazy_compile();
        parse_info.set_collect_source_positions();
        if (FLAG_allow_natives_syntax)
            parse_info.set_allow_natives_syntax();

        // Parse and update ParseInfo with the results.
        if (!parsing::ParseAny(&parse_info, shared_info, isolate)) {
            // Parsing failed probably as a result of stack exhaustion.
            bytecode->SetSourcePositionsFailedToCollect();
            return FailWithPendingException(
                isolate, &parse_info, Compiler::ClearExceptionFlag::CLEAR_EXCEPTION);
        }

        // Generate the unoptimized bytecode.
        // TODO(v8:8510): Consider forcing preparsing of inner functions to avoid
        // wasting time fully parsing them when they won't ever be used.
        UnoptimizedCompilationJobList inner_function_jobs;
        std::unique_ptr<UnoptimizedCompilationJob> outer_function_job(
            GenerateUnoptimizedCode(&parse_info, isolate->allocator(),
                &inner_function_jobs));
        if (!outer_function_job) {
            // Recompiling failed probably as a result of stack exhaustion.
            bytecode->SetSourcePositionsFailedToCollect();
            return FailWithPendingException(
                isolate, &parse_info, Compiler::ClearExceptionFlag::CLEAR_EXCEPTION);
        }

        DCHECK(outer_function_job->compilation_info()->collect_source_positions());

        // TODO(v8:8510) Avoid re-allocating bytecode array/constant pool and
        // re-internalizeing the ast values. Maybe we could use the
        // unoptimized_compilation_flag to signal that all we need is the source
        // position table (and we could do the DCHECK that the bytecode array is the
        // same in the bytecode-generator, by comparing the real bytecode array on the
        // SFI with the off-heap bytecode array).

        // Internalize ast values onto the heap.
        parse_info.ast_value_factory()->Internalize(isolate);

        {
            // Allocate scope infos for the literal.
            DeclarationScope::AllocateScopeInfos(&parse_info, isolate);
            CHECK_EQ(outer_function_job->FinalizeJob(shared_info, isolate),
                CompilationJob::SUCCEEDED);
        }

        // Update the source position table on the original bytecode.
        DCHECK(bytecode->IsBytecodeEqual(
            *outer_function_job->compilation_info()->bytecode_array()));
        DCHECK(outer_function_job->compilation_info()->has_bytecode_array());
        ByteArray source_position_table = outer_function_job->compilation_info()
                                              ->bytecode_array()
                                              ->SourcePositionTable();
        bytecode->set_source_position_table(source_position_table);
        // If debugging, make sure that instrumented bytecode has the source position
        // table set on it as well.
        if (shared_info->HasDebugInfo() && shared_info->GetDebugInfo()->HasInstrumentedBytecodeArray()) {
            shared_info->GetDebugBytecodeArray()->set_source_position_table(
                source_position_table);
        }

        DCHECK(!isolate->has_pending_exception());
        DCHECK(shared_info->is_compiled_scope().is_compiled());
        return true;
    }

    bool Compiler::Compile(Handle<SharedFunctionInfo> shared_info,
        ClearExceptionFlag flag,
        IsCompiledScope* is_compiled_scope)
    {
        // We should never reach here if the function is already compiled.
        DCHECK(!shared_info->is_compiled());
        DCHECK(!is_compiled_scope->is_compiled());

        Isolate* isolate = shared_info->GetIsolate();
        DCHECK(AllowCompilation::IsAllowed(isolate));
        DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
        DCHECK(!isolate->has_pending_exception());
        DCHECK(!shared_info->HasBytecodeArray());
        VMState<BYTECODE_COMPILER> state(isolate);
        PostponeInterruptsScope postpone(isolate);
        TimerEventScope<TimerEventCompileCode> compile_timer(isolate);
        RuntimeCallTimerScope runtimeTimer(isolate,
            RuntimeCallCounterId::kCompileFunction);
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileCode");
        AggregatedHistogramTimerScope timer(isolate->counters()->compile_lazy());

        // Set up parse info.
        ParseInfo parse_info(isolate, shared_info);
        parse_info.set_lazy_compile();

        // Check if the compiler dispatcher has shared_info enqueued for compile.
        CompilerDispatcher* dispatcher = isolate->compiler_dispatcher();
        if (dispatcher->IsEnqueued(shared_info)) {
            if (!dispatcher->FinishNow(shared_info)) {
                return FailWithPendingException(isolate, &parse_info, flag);
            }
            *is_compiled_scope = shared_info->is_compiled_scope();
            DCHECK(is_compiled_scope->is_compiled());
            return true;
        }

        if (shared_info->HasUncompiledDataWithPreparseData()) {
            parse_info.set_consumed_preparse_data(ConsumedPreparseData::For(
                isolate,
                handle(
                    shared_info->uncompiled_data_with_preparse_data()->preparse_data(),
                    isolate)));
        }

        // Parse and update ParseInfo with the results.
        if (!parsing::ParseAny(&parse_info, shared_info, isolate)) {
            return FailWithPendingException(isolate, &parse_info, flag);
        }

        // Generate the unoptimized bytecode or asm-js data.
        UnoptimizedCompilationJobList inner_function_jobs;
        std::unique_ptr<UnoptimizedCompilationJob> outer_function_job(
            GenerateUnoptimizedCode(&parse_info, isolate->allocator(),
                &inner_function_jobs));
        if (!outer_function_job) {
            return FailWithPendingException(isolate, &parse_info, flag);
        }

        // Internalize ast values onto the heap.
        parse_info.ast_value_factory()->Internalize(isolate);

        // Finalize compilation of the unoptimized bytecode or asm-js data.
        if (!FinalizeUnoptimizedCode(&parse_info, isolate, shared_info,
                outer_function_job.get(),
                &inner_function_jobs)) {
            return FailWithPendingException(isolate, &parse_info, flag);
        }

        DCHECK(!isolate->has_pending_exception());
        *is_compiled_scope = shared_info->is_compiled_scope();
        DCHECK(is_compiled_scope->is_compiled());
        return true;
    }

    bool Compiler::Compile(Handle<JSFunction> function, ClearExceptionFlag flag,
        IsCompiledScope* is_compiled_scope)
    {
        // We should never reach here if the function is already compiled or optimized
        DCHECK(!function->is_compiled());
        DCHECK(!function->IsOptimized());
        DCHECK(!function->HasOptimizationMarker());
        DCHECK(!function->HasOptimizedCode());

        // Reset the JSFunction if we are recompiling due to the bytecode having been
        // flushed.
        function->ResetIfBytecodeFlushed();

        Isolate* isolate = function->GetIsolate();
        Handle<SharedFunctionInfo> shared_info = handle(function->shared(), isolate);

        // Ensure shared function info is compiled.
        *is_compiled_scope = shared_info->is_compiled_scope();
        if (!is_compiled_scope->is_compiled() && !Compile(shared_info, flag, is_compiled_scope)) {
            return false;
        }
        DCHECK(is_compiled_scope->is_compiled());
        Handle<Code> code = handle(shared_info->GetCode(), isolate);

        // Initialize the feedback cell for this JSFunction.
        JSFunction::InitializeFeedbackCell(function);

        // Optimize now if --always-opt is enabled.
        if (FLAG_always_opt && !function->shared()->HasAsmWasmData()) {
            if (FLAG_trace_opt) {
                PrintF("[optimizing ");
                function->ShortPrint();
                PrintF(" because --always-opt]\n");
            }
            Handle<Code> opt_code;
            if (GetOptimizedCode(function, ConcurrencyMode::kNotConcurrent)
                    .ToHandle(&opt_code)) {
                code = opt_code;
            }
        }

        // Install code on closure.
        function->set_code(*code);

        // Check postconditions on success.
        DCHECK(!isolate->has_pending_exception());
        DCHECK(function->shared()->is_compiled());
        DCHECK(function->is_compiled());
        return true;
    }

    bool Compiler::FinalizeBackgroundCompileTask(
        BackgroundCompileTask* task, Handle<SharedFunctionInfo> shared_info,
        Isolate* isolate, ClearExceptionFlag flag)
    {
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
            "V8.FinalizeBackgroundCompileTask");
        RuntimeCallTimerScope runtimeTimer(
            isolate, RuntimeCallCounterId::kCompileFinalizeBackgroundCompileTask);
        HandleScope scope(isolate);
        ParseInfo* parse_info = task->info();
        DCHECK(!parse_info->is_toplevel());
        DCHECK(!shared_info->is_compiled());

        Handle<Script> script(Script::cast(shared_info->script()), isolate);
        parse_info->set_script(script);

        task->parser()->UpdateStatistics(isolate, script);
        task->parser()->HandleSourceURLComments(isolate, script);

        if (parse_info->literal() == nullptr || !task->outer_function_job()) {
            // Parsing or compile failed on background thread - report error messages.
            return FailWithPendingException(isolate, parse_info, flag);
        }

        // Parsing has succeeded - finalize compilation.
        parse_info->ast_value_factory()->Internalize(isolate);
        if (!FinalizeUnoptimizedCode(parse_info, isolate, shared_info,
                task->outer_function_job(),
                task->inner_function_jobs())) {
            // Finalization failed - throw an exception.
            return FailWithPendingException(isolate, parse_info, flag);
        }

        DCHECK(!isolate->has_pending_exception());
        DCHECK(shared_info->is_compiled());
        return true;
    }

    bool Compiler::CompileOptimized(Handle<JSFunction> function,
        ConcurrencyMode mode)
    {
        if (function->IsOptimized())
            return true;
        Isolate* isolate = function->GetIsolate();
        DCHECK(AllowCompilation::IsAllowed(isolate));

        // Start a compilation.
        Handle<Code> code;
        if (!GetOptimizedCode(function, mode).ToHandle(&code)) {
            // Optimization failed, get unoptimized code. Unoptimized code must exist
            // already if we are optimizing.
            DCHECK(!isolate->has_pending_exception());
            DCHECK(function->shared()->is_compiled());
            DCHECK(function->shared()->IsInterpreted());
            code = BUILTIN_CODE(isolate, InterpreterEntryTrampoline);
        }

        // Install code on closure.
        function->set_code(*code);

        // Check postconditions on success.
        DCHECK(!isolate->has_pending_exception());
        DCHECK(function->shared()->is_compiled());
        DCHECK(function->is_compiled());
        DCHECK_IMPLIES(function->HasOptimizationMarker(),
            function->IsInOptimizationQueue());
        DCHECK_IMPLIES(function->HasOptimizationMarker(),
            function->ChecksOptimizationMarker());
        DCHECK_IMPLIES(function->IsInOptimizationQueue(),
            mode == ConcurrencyMode::kConcurrent);
        return true;
    }

    MaybeHandle<SharedFunctionInfo> Compiler::CompileForLiveEdit(
        ParseInfo* parse_info, Isolate* isolate)
    {
        IsCompiledScope is_compiled_scope;
        return CompileToplevel(parse_info, isolate, &is_compiled_scope);
    }

    MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
        Handle<String> source, Handle<SharedFunctionInfo> outer_info,
        Handle<Context> context, LanguageMode language_mode,
        ParseRestriction restriction, int parameters_end_pos,
        int eval_scope_position, int eval_position)
    {
        Isolate* isolate = context->GetIsolate();
        int source_length = source->length();
        isolate->counters()->total_eval_size()->Increment(source_length);
        isolate->counters()->total_compile_size()->Increment(source_length);

        // The cache lookup key needs to be aware of the separation between the
        // parameters and the body to prevent this valid invocation:
        //   Function("", "function anonymous(\n/**/) {\n}");
        // from adding an entry that falsely approves this invalid invocation:
        //   Function("\n/**/) {\nfunction anonymous(", "}");
        // The actual eval_scope_position for indirect eval and CreateDynamicFunction
        // is unused (just 0), which means it's an available field to use to indicate
        // this separation. But to make sure we're not causing other false hits, we
        // negate the scope position.
        if (restriction == ONLY_SINGLE_FUNCTION_LITERAL && parameters_end_pos != kNoSourcePosition) {
            // use the parameters_end_pos as the eval_scope_position in the eval cache.
            DCHECK_EQ(eval_scope_position, 0);
            eval_scope_position = -parameters_end_pos;
        }
        CompilationCache* compilation_cache = isolate->compilation_cache();
        InfoCellPair eval_result = compilation_cache->LookupEval(
            source, outer_info, context, language_mode, eval_scope_position);
        Handle<FeedbackCell> feedback_cell;
        if (eval_result.has_feedback_cell()) {
            feedback_cell = handle(eval_result.feedback_cell(), isolate);
        }

        Handle<SharedFunctionInfo> shared_info;
        Handle<Script> script;
        IsCompiledScope is_compiled_scope;
        bool allow_eval_cache;
        if (eval_result.has_shared()) {
            shared_info = Handle<SharedFunctionInfo>(eval_result.shared(), isolate);
            script = Handle<Script>(Script::cast(shared_info->script()), isolate);
            is_compiled_scope = shared_info->is_compiled_scope();
            allow_eval_cache = true;
        } else {
            ParseInfo parse_info(isolate);
            script = parse_info.CreateScript(
                isolate, source, OriginOptionsForEval(outer_info->script()));
            script->set_compilation_type(Script::COMPILATION_TYPE_EVAL);
            script->set_eval_from_shared(*outer_info);
            if (eval_position == kNoSourcePosition) {
                // If the position is missing, attempt to get the code offset by
                // walking the stack. Do not translate the code offset into source
                // position, but store it as negative value for lazy translation.
                StackTraceFrameIterator it(isolate);
                if (!it.done() && it.is_javascript()) {
                    FrameSummary summary = FrameSummary::GetTop(it.javascript_frame());
                    script->set_eval_from_shared(
                        summary.AsJavaScript().function()->shared());
                    script->set_origin_options(OriginOptionsForEval(*summary.script()));
                    eval_position = -summary.code_offset();
                } else {
                    eval_position = 0;
                }
            }
            script->set_eval_from_position(eval_position);
            TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
                TRACE_DISABLED_BY_DEFAULT("v8.compile"), "Script",
                TRACE_ID_WITH_SCOPE(Script::kTraceScope, script->id()),
                script->ToTracedValue());

            parse_info.set_eval();
            parse_info.set_language_mode(language_mode);
            parse_info.set_parse_restriction(restriction);
            parse_info.set_parameters_end_pos(parameters_end_pos);
            if (!context->IsNativeContext()) {
                parse_info.set_outer_scope_info(handle(context->scope_info(), isolate));
            }
            DCHECK(!parse_info.is_module());

            if (!CompileToplevel(&parse_info, isolate, &is_compiled_scope)
                     .ToHandle(&shared_info)) {
                return MaybeHandle<JSFunction>();
            }
            allow_eval_cache = parse_info.allow_eval_cache();
        }

        // If caller is strict mode, the result must be in strict mode as well.
        DCHECK(is_sloppy(language_mode) || is_strict(shared_info->language_mode()));

        Handle<JSFunction> result;
        if (eval_result.has_shared()) {
            if (eval_result.has_feedback_cell()) {
                result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
                    shared_info, context, feedback_cell, AllocationType::kYoung);
            } else {
                result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
                    shared_info, context, AllocationType::kYoung);
                JSFunction::InitializeFeedbackCell(result);
                if (allow_eval_cache) {
                    // Make sure to cache this result.
                    Handle<FeedbackCell> new_feedback_cell(result->raw_feedback_cell(),
                        isolate);
                    compilation_cache->PutEval(source, outer_info, context, shared_info,
                        new_feedback_cell, eval_scope_position);
                }
            }
        } else {
            result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
                shared_info, context, AllocationType::kYoung);
            JSFunction::InitializeFeedbackCell(result);
            if (allow_eval_cache) {
                // Add the SharedFunctionInfo and the LiteralsArray to the eval cache if
                // we didn't retrieve from there.
                Handle<FeedbackCell> new_feedback_cell(result->raw_feedback_cell(),
                    isolate);
                compilation_cache->PutEval(source, outer_info, context, shared_info,
                    new_feedback_cell, eval_scope_position);
            }
        }
        DCHECK(is_compiled_scope.is_compiled());

        return result;
    }

    bool Compiler::CodeGenerationFromStringsAllowed(Isolate* isolate,
        Handle<Context> context,
        Handle<String> source)
    {
        DCHECK(context->allow_code_gen_from_strings()->IsFalse(isolate));
        // Check with callback if set.
        AllowCodeGenerationFromStringsCallback callback = isolate->allow_code_gen_callback();
        if (callback == nullptr) {
            // No callback set and code generation disallowed.
            return false;
        } else {
            // Callback set. Let it decide if code generation is allowed.
            VMState<EXTERNAL> state(isolate);
            return callback(v8::Utils::ToLocal(context), v8::Utils::ToLocal(source));
        }
    }

    MaybeHandle<JSFunction> Compiler::GetFunctionFromString(
        Handle<Context> context, Handle<String> source,
        ParseRestriction restriction, int parameters_end_pos)
    {
        Isolate* const isolate = context->GetIsolate();
        Handle<Context> native_context(context->native_context(), isolate);

        // Check if native context allows code generation from
        // strings. Throw an exception if it doesn't.
        if (native_context->allow_code_gen_from_strings()->IsFalse(isolate) && !CodeGenerationFromStringsAllowed(isolate, native_context, source)) {
            Handle<Object> error_message = native_context->ErrorMessageForCodeGenerationFromStrings();
            THROW_NEW_ERROR(isolate, NewEvalError(MessageTemplate::kCodeGenFromStrings, error_message),
                JSFunction);
        }

        // Compile source string in the native context.
        int eval_scope_position = 0;
        int eval_position = kNoSourcePosition;
        Handle<SharedFunctionInfo> outer_info(
            native_context->empty_function()->shared(), isolate);
        return Compiler::GetFunctionFromEval(
            source, outer_info, native_context, LanguageMode::kSloppy, restriction,
            parameters_end_pos, eval_scope_position, eval_position);
    }

    namespace {

        struct ScriptCompileTimerScope {
        public:
            // TODO(leszeks): There are too many blink-specific entries in this enum,
            // figure out a way to push produce/hit-isolate-cache/consume/consume-failed
            // back up the API and log them in blink instead.
            enum class CacheBehaviour {
                kProduceCodeCache,
                kHitIsolateCacheWhenNoCache,
                kConsumeCodeCache,
                kConsumeCodeCacheFailed,
                kNoCacheBecauseInlineScript,
                kNoCacheBecauseScriptTooSmall,
                kNoCacheBecauseCacheTooCold,
                kNoCacheNoReason,
                kNoCacheBecauseNoResource,
                kNoCacheBecauseInspector,
                kNoCacheBecauseCachingDisabled,
                kNoCacheBecauseModule,
                kNoCacheBecauseStreamingSource,
                kNoCacheBecauseV8Extension,
                kHitIsolateCacheWhenProduceCodeCache,
                kHitIsolateCacheWhenConsumeCodeCache,
                kNoCacheBecauseExtensionModule,
                kNoCacheBecausePacScript,
                kNoCacheBecauseInDocumentWrite,
                kNoCacheBecauseResourceWithNoCacheHandler,
                kHitIsolateCacheWhenStreamingSource,
                kCount
            };

            explicit ScriptCompileTimerScope(
                Isolate* isolate, ScriptCompiler::NoCacheReason no_cache_reason)
                : isolate_(isolate)
                , all_scripts_histogram_scope_(isolate->counters()->compile_script(),
                      true)
                , no_cache_reason_(no_cache_reason)
                , hit_isolate_cache_(false)
                , producing_code_cache_(false)
                , consuming_code_cache_(false)
                , consuming_code_cache_failed_(false)
            {
            }

            ~ScriptCompileTimerScope()
            {
                CacheBehaviour cache_behaviour = GetCacheBehaviour();

                Histogram* cache_behaviour_histogram = isolate_->counters()->compile_script_cache_behaviour();
                // Sanity check that the histogram has exactly one bin per enum entry.
                DCHECK_EQ(0, cache_behaviour_histogram->min());
                DCHECK_EQ(static_cast<int>(CacheBehaviour::kCount),
                    cache_behaviour_histogram->max() + 1);
                DCHECK_EQ(static_cast<int>(CacheBehaviour::kCount),
                    cache_behaviour_histogram->num_buckets());
                cache_behaviour_histogram->AddSample(static_cast<int>(cache_behaviour));

                histogram_scope_.set_histogram(
                    GetCacheBehaviourTimedHistogram(cache_behaviour));
            }

            void set_hit_isolate_cache() { hit_isolate_cache_ = true; }

            void set_producing_code_cache() { producing_code_cache_ = true; }

            void set_consuming_code_cache() { consuming_code_cache_ = true; }

            void set_consuming_code_cache_failed()
            {
                consuming_code_cache_failed_ = true;
            }

        private:
            Isolate* isolate_;
            LazyTimedHistogramScope histogram_scope_;
            // TODO(leszeks): This timer is the sum of the other times, consider removing
            // it to save space.
            HistogramTimerScope all_scripts_histogram_scope_;
            ScriptCompiler::NoCacheReason no_cache_reason_;
            bool hit_isolate_cache_;
            bool producing_code_cache_;
            bool consuming_code_cache_;
            bool consuming_code_cache_failed_;

            CacheBehaviour GetCacheBehaviour()
            {
                if (producing_code_cache_) {
                    if (hit_isolate_cache_) {
                        return CacheBehaviour::kHitIsolateCacheWhenProduceCodeCache;
                    } else {
                        return CacheBehaviour::kProduceCodeCache;
                    }
                }

                if (consuming_code_cache_) {
                    if (hit_isolate_cache_) {
                        return CacheBehaviour::kHitIsolateCacheWhenConsumeCodeCache;
                    } else if (consuming_code_cache_failed_) {
                        return CacheBehaviour::kConsumeCodeCacheFailed;
                    }
                    return CacheBehaviour::kConsumeCodeCache;
                }

                if (hit_isolate_cache_) {
                    if (no_cache_reason_ == ScriptCompiler::kNoCacheBecauseStreamingSource) {
                        return CacheBehaviour::kHitIsolateCacheWhenStreamingSource;
                    }
                    return CacheBehaviour::kHitIsolateCacheWhenNoCache;
                }

                switch (no_cache_reason_) {
                case ScriptCompiler::kNoCacheBecauseInlineScript:
                    return CacheBehaviour::kNoCacheBecauseInlineScript;
                case ScriptCompiler::kNoCacheBecauseScriptTooSmall:
                    return CacheBehaviour::kNoCacheBecauseScriptTooSmall;
                case ScriptCompiler::kNoCacheBecauseCacheTooCold:
                    return CacheBehaviour::kNoCacheBecauseCacheTooCold;
                case ScriptCompiler::kNoCacheNoReason:
                    return CacheBehaviour::kNoCacheNoReason;
                case ScriptCompiler::kNoCacheBecauseNoResource:
                    return CacheBehaviour::kNoCacheBecauseNoResource;
                case ScriptCompiler::kNoCacheBecauseInspector:
                    return CacheBehaviour::kNoCacheBecauseInspector;
                case ScriptCompiler::kNoCacheBecauseCachingDisabled:
                    return CacheBehaviour::kNoCacheBecauseCachingDisabled;
                case ScriptCompiler::kNoCacheBecauseModule:
                    return CacheBehaviour::kNoCacheBecauseModule;
                case ScriptCompiler::kNoCacheBecauseStreamingSource:
                    return CacheBehaviour::kNoCacheBecauseStreamingSource;
                case ScriptCompiler::kNoCacheBecauseV8Extension:
                    return CacheBehaviour::kNoCacheBecauseV8Extension;
                case ScriptCompiler::kNoCacheBecauseExtensionModule:
                    return CacheBehaviour::kNoCacheBecauseExtensionModule;
                case ScriptCompiler::kNoCacheBecausePacScript:
                    return CacheBehaviour::kNoCacheBecausePacScript;
                case ScriptCompiler::kNoCacheBecauseInDocumentWrite:
                    return CacheBehaviour::kNoCacheBecauseInDocumentWrite;
                case ScriptCompiler::kNoCacheBecauseResourceWithNoCacheHandler:
                    return CacheBehaviour::kNoCacheBecauseResourceWithNoCacheHandler;
                case ScriptCompiler::kNoCacheBecauseDeferredProduceCodeCache: {
                    if (hit_isolate_cache_) {
                        return CacheBehaviour::kHitIsolateCacheWhenProduceCodeCache;
                    } else {
                        return CacheBehaviour::kProduceCodeCache;
                    }
                }
                }
                UNREACHABLE();
            }

            TimedHistogram* GetCacheBehaviourTimedHistogram(
                CacheBehaviour cache_behaviour)
            {
                switch (cache_behaviour) {
                case CacheBehaviour::kProduceCodeCache:
                // Even if we hit the isolate's compilation cache, we currently recompile
                // when we want to produce the code cache.
                case CacheBehaviour::kHitIsolateCacheWhenProduceCodeCache:
                    return isolate_->counters()->compile_script_with_produce_cache();
                case CacheBehaviour::kHitIsolateCacheWhenNoCache:
                case CacheBehaviour::kHitIsolateCacheWhenConsumeCodeCache:
                case CacheBehaviour::kHitIsolateCacheWhenStreamingSource:
                    return isolate_->counters()->compile_script_with_isolate_cache_hit();
                case CacheBehaviour::kConsumeCodeCacheFailed:
                    return isolate_->counters()->compile_script_consume_failed();
                case CacheBehaviour::kConsumeCodeCache:
                    return isolate_->counters()->compile_script_with_consume_cache();

                case CacheBehaviour::kNoCacheBecauseInlineScript:
                    return isolate_->counters()
                        ->compile_script_no_cache_because_inline_script();
                case CacheBehaviour::kNoCacheBecauseScriptTooSmall:
                    return isolate_->counters()
                        ->compile_script_no_cache_because_script_too_small();
                case CacheBehaviour::kNoCacheBecauseCacheTooCold:
                    return isolate_->counters()
                        ->compile_script_no_cache_because_cache_too_cold();

                // Aggregate all the other "no cache" counters into a single histogram, to
                // save space.
                case CacheBehaviour::kNoCacheNoReason:
                case CacheBehaviour::kNoCacheBecauseNoResource:
                case CacheBehaviour::kNoCacheBecauseInspector:
                case CacheBehaviour::kNoCacheBecauseCachingDisabled:
                // TODO(leszeks): Consider counting separately once modules are more
                // common.
                case CacheBehaviour::kNoCacheBecauseModule:
                // TODO(leszeks): Count separately or remove entirely once we have
                // background compilation.
                case CacheBehaviour::kNoCacheBecauseStreamingSource:
                case CacheBehaviour::kNoCacheBecauseV8Extension:
                case CacheBehaviour::kNoCacheBecauseExtensionModule:
                case CacheBehaviour::kNoCacheBecausePacScript:
                case CacheBehaviour::kNoCacheBecauseInDocumentWrite:
                case CacheBehaviour::kNoCacheBecauseResourceWithNoCacheHandler:
                    return isolate_->counters()->compile_script_no_cache_other();

                case CacheBehaviour::kCount:
                    UNREACHABLE();
                }
                UNREACHABLE();
            }
        };

        Handle<Script> NewScript(Isolate* isolate, ParseInfo* parse_info,
            Handle<String> source,
            Compiler::ScriptDetails script_details,
            ScriptOriginOptions origin_options,
            NativesFlag natives)
        {
            // Create a script object describing the script to be compiled.
            Handle<Script> script = parse_info->CreateScript(isolate, source, origin_options, natives);
            Handle<Object> script_name;
            if (script_details.name_obj.ToHandle(&script_name)) {
                script->set_name(*script_name);
                script->set_line_offset(script_details.line_offset);
                script->set_column_offset(script_details.column_offset);
            }
            Handle<Object> source_map_url;
            if (script_details.source_map_url.ToHandle(&source_map_url)) {
                script->set_source_mapping_url(*source_map_url);
            }
            Handle<FixedArray> host_defined_options;
            if (script_details.host_defined_options.ToHandle(&host_defined_options)) {
                script->set_host_defined_options(*host_defined_options);
            }
            LOG(isolate, ScriptDetails(*script));
            TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
                TRACE_DISABLED_BY_DEFAULT("v8.compile"), "Script",
                TRACE_ID_WITH_SCOPE(Script::kTraceScope, script->id()),
                script->ToTracedValue());
            return script;
        }

    } // namespace

    MaybeHandle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForScript(
        Isolate* isolate, Handle<String> source,
        const Compiler::ScriptDetails& script_details,
        ScriptOriginOptions origin_options, v8::Extension* extension,
        ScriptData* cached_data, ScriptCompiler::CompileOptions compile_options,
        ScriptCompiler::NoCacheReason no_cache_reason, NativesFlag natives)
    {
        ScriptCompileTimerScope compile_timer(isolate, no_cache_reason);

        if (compile_options == ScriptCompiler::kNoCompileOptions || compile_options == ScriptCompiler::kEagerCompile) {
            DCHECK_NULL(cached_data);
        } else {
            DCHECK(compile_options == ScriptCompiler::kConsumeCodeCache);
            DCHECK(cached_data);
            DCHECK_NULL(extension);
        }
        int source_length = source->length();
        isolate->counters()->total_load_size()->Increment(source_length);
        isolate->counters()->total_compile_size()->Increment(source_length);

        LanguageMode language_mode = construct_language_mode(FLAG_use_strict);
        CompilationCache* compilation_cache = isolate->compilation_cache();

        // Do a lookup in the compilation cache but not for extensions.
        MaybeHandle<SharedFunctionInfo> maybe_result;
        IsCompiledScope is_compiled_scope;
        if (extension == nullptr) {
            bool can_consume_code_cache = compile_options == ScriptCompiler::kConsumeCodeCache;
            if (can_consume_code_cache) {
                compile_timer.set_consuming_code_cache();
            }

            // First check per-isolate compilation cache.
            maybe_result = compilation_cache->LookupScript(
                source, script_details.name_obj, script_details.line_offset,
                script_details.column_offset, origin_options, isolate->native_context(),
                language_mode);
            if (!maybe_result.is_null()) {
                compile_timer.set_hit_isolate_cache();
            } else if (can_consume_code_cache) {
                compile_timer.set_consuming_code_cache();
                // Then check cached code provided by embedder.
                HistogramTimerScope timer(isolate->counters()->compile_deserialize());
                RuntimeCallTimerScope runtimeTimer(
                    isolate, RuntimeCallCounterId::kCompileDeserialize);
                TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                    "V8.CompileDeserialize");
                Handle<SharedFunctionInfo> inner_result;
                if (CodeSerializer::Deserialize(isolate, cached_data, source,
                        origin_options)
                        .ToHandle(&inner_result)
                    && inner_result->is_compiled()) {
                    // Promote to per-isolate compilation cache.
                    is_compiled_scope = inner_result->is_compiled_scope();
                    DCHECK(is_compiled_scope.is_compiled());
                    compilation_cache->PutScript(source, isolate->native_context(),
                        language_mode, inner_result);
                    Handle<Script> script(Script::cast(inner_result->script()), isolate);
                    maybe_result = inner_result;
                } else {
                    // Deserializer failed. Fall through to compile.
                    compile_timer.set_consuming_code_cache_failed();
                }
            }
        }

        if (maybe_result.is_null()) {
            ParseInfo parse_info(isolate);
            // No cache entry found compile the script.
            NewScript(isolate, &parse_info, source, script_details, origin_options,
                natives);

            // Compile the function and add it to the isolate cache.
            if (origin_options.IsModule())
                parse_info.set_module();
            parse_info.set_extension(extension);
            parse_info.set_eager(compile_options == ScriptCompiler::kEagerCompile);

            parse_info.set_language_mode(
                stricter_language_mode(parse_info.language_mode(), language_mode));
            maybe_result = CompileToplevel(&parse_info, isolate, &is_compiled_scope);
            Handle<SharedFunctionInfo> result;
            if (extension == nullptr && maybe_result.ToHandle(&result)) {
                DCHECK(is_compiled_scope.is_compiled());
                compilation_cache->PutScript(source, isolate->native_context(),
                    language_mode, result);
            } else if (maybe_result.is_null() && natives != EXTENSION_CODE) {
                isolate->ReportPendingMessages();
            }
        }

        return maybe_result;
    }

    MaybeHandle<JSFunction> Compiler::GetWrappedFunction(
        Handle<String> source, Handle<FixedArray> arguments,
        Handle<Context> context, const Compiler::ScriptDetails& script_details,
        ScriptOriginOptions origin_options, ScriptData* cached_data,
        v8::ScriptCompiler::CompileOptions compile_options,
        v8::ScriptCompiler::NoCacheReason no_cache_reason)
    {
        Isolate* isolate = context->GetIsolate();
        ScriptCompileTimerScope compile_timer(isolate, no_cache_reason);

        if (compile_options == ScriptCompiler::kNoCompileOptions || compile_options == ScriptCompiler::kEagerCompile) {
            DCHECK_NULL(cached_data);
        } else {
            DCHECK(compile_options == ScriptCompiler::kConsumeCodeCache);
            DCHECK(cached_data);
        }

        int source_length = source->length();
        isolate->counters()->total_compile_size()->Increment(source_length);

        LanguageMode language_mode = construct_language_mode(FLAG_use_strict);

        MaybeHandle<SharedFunctionInfo> maybe_result;
        bool can_consume_code_cache = compile_options == ScriptCompiler::kConsumeCodeCache;
        if (can_consume_code_cache) {
            compile_timer.set_consuming_code_cache();
            // Then check cached code provided by embedder.
            HistogramTimerScope timer(isolate->counters()->compile_deserialize());
            RuntimeCallTimerScope runtimeTimer(
                isolate, RuntimeCallCounterId::kCompileDeserialize);
            TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.CompileDeserialize");
            maybe_result = CodeSerializer::Deserialize(isolate, cached_data, source,
                origin_options);
            if (maybe_result.is_null()) {
                // Deserializer failed. Fall through to compile.
                compile_timer.set_consuming_code_cache_failed();
            }
        }

        Handle<SharedFunctionInfo> wrapped;
        Handle<Script> script;
        IsCompiledScope is_compiled_scope;
        if (!maybe_result.ToHandle(&wrapped)) {
            ParseInfo parse_info(isolate);
            script = NewScript(isolate, &parse_info, source, script_details,
                origin_options, NOT_NATIVES_CODE);
            script->set_wrapped_arguments(*arguments);

            parse_info.set_eval(); // Use an eval scope as declaration scope.
            parse_info.set_wrapped_as_function();
            // parse_info.set_eager(compile_options == ScriptCompiler::kEagerCompile);
            if (!context->IsNativeContext()) {
                parse_info.set_outer_scope_info(handle(context->scope_info(), isolate));
            }
            parse_info.set_language_mode(
                stricter_language_mode(parse_info.language_mode(), language_mode));

            Handle<SharedFunctionInfo> top_level;
            maybe_result = CompileToplevel(&parse_info, isolate, &is_compiled_scope);
            if (maybe_result.is_null())
                isolate->ReportPendingMessages();
            ASSIGN_RETURN_ON_EXCEPTION(isolate, top_level, maybe_result, JSFunction);

            SharedFunctionInfo::ScriptIterator infos(isolate, *script);
            for (SharedFunctionInfo info = infos.Next(); !info.is_null();
                 info = infos.Next()) {
                if (info->is_wrapped()) {
                    wrapped = Handle<SharedFunctionInfo>(info, isolate);
                    break;
                }
            }
            DCHECK(!wrapped.is_null());
        } else {
            is_compiled_scope = wrapped->is_compiled_scope();
            script = Handle<Script>(Script::cast(wrapped->script()), isolate);
        }
        DCHECK(is_compiled_scope.is_compiled());

        return isolate->factory()->NewFunctionFromSharedFunctionInfo(
            wrapped, context, AllocationType::kYoung);
    }

    MaybeHandle<SharedFunctionInfo>
    Compiler::GetSharedFunctionInfoForStreamedScript(
        Isolate* isolate, Handle<String> source,
        const ScriptDetails& script_details, ScriptOriginOptions origin_options,
        ScriptStreamingData* streaming_data)
    {
        ScriptCompileTimerScope compile_timer(
            isolate, ScriptCompiler::kNoCacheBecauseStreamingSource);
        PostponeInterruptsScope postpone(isolate);

        int source_length = source->length();
        isolate->counters()->total_load_size()->Increment(source_length);
        isolate->counters()->total_compile_size()->Increment(source_length);

        BackgroundCompileTask* task = streaming_data->task.get();
        ParseInfo* parse_info = task->info();
        DCHECK(parse_info->is_toplevel());
        // Check if compile cache already holds the SFI, if so no need to finalize
        // the code compiled on the background thread.
        CompilationCache* compilation_cache = isolate->compilation_cache();
        MaybeHandle<SharedFunctionInfo> maybe_result = compilation_cache->LookupScript(
            source, script_details.name_obj, script_details.line_offset,
            script_details.column_offset, origin_options,
            isolate->native_context(), parse_info->language_mode());
        if (!maybe_result.is_null()) {
            compile_timer.set_hit_isolate_cache();
        }

        if (maybe_result.is_null()) {
            // No cache entry found, finalize compilation of the script and add it to
            // the isolate cache.
            Handle<Script> script = NewScript(isolate, parse_info, source, script_details, origin_options,
                NOT_NATIVES_CODE);
            task->parser()->UpdateStatistics(isolate, script);
            task->parser()->HandleSourceURLComments(isolate, script);

            if (parse_info->literal() == nullptr || !task->outer_function_job()) {
                // Parsing has failed - report error messages.
                FailWithPendingException(isolate, parse_info,
                    Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
            } else {
                // Parsing has succeeded - finalize compilation.
                maybe_result = FinalizeTopLevel(parse_info, isolate, task->outer_function_job(),
                    task->inner_function_jobs());
                if (maybe_result.is_null()) {
                    // Finalization failed - throw an exception.
                    FailWithPendingException(isolate, parse_info,
                        Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
                }
            }

            // Add compiled code to the isolate cache.
            Handle<SharedFunctionInfo> result;
            if (maybe_result.ToHandle(&result)) {
                compilation_cache->PutScript(source, isolate->native_context(),
                    parse_info->language_mode(), result);
            }
        }

        streaming_data->Release();
        return maybe_result;
    }

    Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
        FunctionLiteral* literal, Handle<Script> script, Isolate* isolate)
    {
        // Precondition: code has been parsed and scopes have been analyzed.
        MaybeHandle<SharedFunctionInfo> maybe_existing;

        // Find any previously allocated shared function info for the given literal.
        maybe_existing = script->FindSharedFunctionInfo(isolate, literal);

        // If we found an existing shared function info, return it.
        Handle<SharedFunctionInfo> existing;
        if (maybe_existing.ToHandle(&existing))
            return existing;

        // Allocate a shared function info object which will be compiled lazily.
        Handle<SharedFunctionInfo> result = isolate->factory()->NewSharedFunctionInfoForLiteral(literal, script,
            false);
        return result;
    }

    MaybeHandle<Code> Compiler::GetOptimizedCodeForOSR(Handle<JSFunction> function,
        BailoutId osr_offset,
        JavaScriptFrame* osr_frame)
    {
        DCHECK(!osr_offset.IsNone());
        DCHECK_NOT_NULL(osr_frame);
        return GetOptimizedCode(function, ConcurrencyMode::kNotConcurrent, osr_offset,
            osr_frame);
    }

    bool Compiler::FinalizeOptimizedCompilationJob(OptimizedCompilationJob* job,
        Isolate* isolate)
    {
        VMState<COMPILER> state(isolate);
        // Take ownership of compilation job.  Deleting job also tears down the zone.
        std::unique_ptr<OptimizedCompilationJob> job_scope(job);
        OptimizedCompilationInfo* compilation_info = job->compilation_info();

        TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
        RuntimeCallTimerScope runtimeTimer(
            isolate, RuntimeCallCounterId::kRecompileSynchronous);
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
            "V8.RecompileSynchronous");

        Handle<SharedFunctionInfo> shared = compilation_info->shared_info();

        // Reset profiler ticks, function is no longer considered hot.
        compilation_info->closure()->feedback_vector()->set_profiler_ticks(0);

        DCHECK(!shared->HasBreakInfo());

        // 1) Optimization on the concurrent thread may have failed.
        // 2) The function may have already been optimized by OSR.  Simply continue.
        //    Except when OSR already disabled optimization for some reason.
        // 3) The code may have already been invalidated due to dependency change.
        // 4) Code generation may have failed.
        if (job->state() == CompilationJob::State::kReadyToFinalize) {
            if (shared->optimization_disabled()) {
                job->RetryOptimization(BailoutReason::kOptimizationDisabled);
            } else if (job->FinalizeJob(isolate) == CompilationJob::SUCCEEDED) {
                job->RecordCompilationStats(OptimizedCompilationJob::kConcurrent,
                    isolate);
                job->RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG,
                    isolate);
                InsertCodeIntoOptimizedCodeCache(compilation_info);
                if (FLAG_trace_opt) {
                    PrintF("[completed optimizing ");
                    compilation_info->closure()->ShortPrint();
                    PrintF("]\n");
                }
                compilation_info->closure()->set_code(*compilation_info->code());
                return CompilationJob::SUCCEEDED;
            }
        }

        DCHECK_EQ(job->state(), CompilationJob::State::kFailed);
        if (FLAG_trace_opt) {
            PrintF("[aborted optimizing ");
            compilation_info->closure()->ShortPrint();
            PrintF(" because: %s]\n",
                GetBailoutReason(compilation_info->bailout_reason()));
        }
        compilation_info->closure()->set_code(shared->GetCode());
        // Clear the InOptimizationQueue marker, if it exists.
        if (compilation_info->closure()->IsInOptimizationQueue()) {
            compilation_info->closure()->ClearOptimizationMarker();
        }
        return CompilationJob::FAILED;
    }

    void Compiler::PostInstantiation(Handle<JSFunction> function,
        AllocationType allocation)
    {
        Isolate* isolate = function->GetIsolate();
        Handle<SharedFunctionInfo> shared(function->shared(), isolate);
        IsCompiledScope is_compiled_scope(shared->is_compiled_scope());

        // If code is compiled to bytecode (i.e., isn't asm.js), then allocate a
        // feedback and check for optimized code.
        if (is_compiled_scope.is_compiled() && shared->HasBytecodeArray()) {
            JSFunction::InitializeFeedbackCell(function);

            Code code = function->has_feedback_vector()
                ? function->feedback_vector()->optimized_code()
                : Code();
            if (!code.is_null()) {
                // Caching of optimized code enabled and optimized code found.
                DCHECK(!code->marked_for_deoptimization());
                DCHECK(function->shared()->is_compiled());
                function->set_code(code);
            }

            if (FLAG_always_opt && shared->allows_lazy_compilation() && !shared->optimization_disabled() && !function->IsOptimized() && !function->HasOptimizedCode()) {
                JSFunction::EnsureFeedbackVector(function);
                function->MarkForOptimization(ConcurrencyMode::kNotConcurrent);
            }
        }

        if (shared->is_toplevel() || shared->is_wrapped()) {
            // If it's a top-level script, report compilation to the debugger.
            Handle<Script> script(Script::cast(shared->script()), isolate);
            isolate->debug()->OnAfterCompile(script);
        }
    }

    // ----------------------------------------------------------------------------
    // Implementation of ScriptStreamingData

    ScriptStreamingData::ScriptStreamingData(
        std::unique_ptr<ScriptCompiler::ExternalSourceStream> source_stream,
        ScriptCompiler::StreamedSource::Encoding encoding)
        : source_stream(std::move(source_stream))
        , encoding(encoding)
    {
    }

    ScriptStreamingData::~ScriptStreamingData() = default;

    void ScriptStreamingData::Release() { task.reset(); }

} // namespace internal
} // namespace v8
